Showing papers by "University of Electro-Communications published in 1981"
TL;DR: The capacity region of a Gaussian interference channel with two separate messages is obtained for the case of moderately strong interference and it is shown that the region coincides with the one where both messages are required in both receiving terminals.
Abstract: The capacity region of a Gaussian interference channel with two separate messages is obtained for the case of moderately strong interference. It is shown that the region coincides with the one where both messages are required in both receiving terminals.
769 citations
TL;DR: In this article, the electronic band structure of chalcopyrite CuFe in the antiferromagnetic phase is calculated by spin-polarized self-consistent charge discrete-variational $X\ensuremath{\alpha}$ method.
Abstract: The electronic band structure of chalcopyrite CuFe${\mathrm{S}}_{2}$ in the antiferromagnetic phase is calculated by spin-polarized self-consistent-charge discrete-variational $X\ensuremath{\alpha}$ method. The valence bands consist of many rather narrow bands constructed from S $3p$, Cu $3d$, and majority-spin Fe $3d$ orbitals. The upper valence bands are constituted mainly of Cu $3d$ and Fe $3d$ orbitals. The top of the valence band is at the $X$ point. The conduction bands composed mainly of $4s$ and $4p$ orbitals of Cu and Fe have the bottom at the $\ensuremath{\Gamma}$ point and the direct gap is 3.1 eV. The narrow bands composed mainly of minority-spin Fe $3d$ orbitals are in the so-called fundamental gap. The direct minimum gap of these $d$ bands is 0.7 eV at the $X$ point. These gap energies are in good agreement with the observed optical spectra. The minimum gap of the minority-spin $d$ bands is indirect and about 0.3 eV. The magnetic moment of an Fe ion is $3.88{\ensuremath{\mu}}_{B}$, which agrees with the observed value.
78 citations
TL;DR: In this paper, an investigation was made of the formation of crystalline SiC thin layers by implantation of carbon ions in silicon and their development, and electron microscopy and diffraction studies showed that α-SiC was formed in some regions of asimplanted layers.
41 citations
TL;DR: In this paper, the dispersion property of microstrip lines was measured in a frequency range from 2 to 50 GHz and compared with that estimated by an approximate formula in a previous paper.
Abstract: The dispersion property of microstrip lines was measured in a frequency range from 2 to 50 GHz and compared with that estimated by an approximate formula in a previous paper.
40 citations
TL;DR: In this article, the shape of true stress-true strain curves in the austenite (y) range is expressed solely in terms of the first stress peak or Z in the following equation, and the relation is almost independent of C content.
Abstract: Synopsis : High temperature tensile deformation of carbon steels containing from 0.036 to 1.09 wt% C was studied in the temperature range 873 to 1 373 K over a wide range of strain rates between 1 and 10-5 s-1. The shape of true stress-true strain (ƒÐ-ƒÃ) curves in the austenite (y) range is expressed solely in terms of the first stress peak (ƒÐp) or Z in the following equation, and the relation is almost independent of C content. up can be correlated with temperature (T) and strain rate (a) by the following equation in the range of stresses below 110,--420 MPa
28 citations
TL;DR: In this article, pressure-induced spin state transitions in Fe(II) compounds are studied on the basis of the ligand field theory by using the model in which the couplings of Fe ion with a molecular distortion and a lattice strain are taken into account.
Abstract: The pressure-induced spin state transitions in Fe(II) compounds are studied on the basis of the ligand field theory by using the model in which the couplings of Fe ion with a molecular distortion and a lattice strain are taken into account. The calculated pressure dependences of the low-spin content reproduce the essential features of the observed several types of transitions: The continuous high-spin (HS) →low-spin (LS) transition with increasing pressure arises from a smooth increasing of the lattice strain with or without a slight change of the molecular distortion. The discontinuous HS →LS transition is due to an abrupt decreasing of the molecular distortion. The LS →HS transition occurs in the case where the lattice strain couples dominantly with Fe ion at lower pressure but the intramolecular coupling overwhelms the strain coupling at higher pressure through an increase of the former induced by pressure.
22 citations
TL;DR: The control engineer, who is responsible for enlarging the scale of automation, should also play a role in adapting it to people as mentioned in this paper. But the control engineer should be individually designed to each culture.
19 citations
Proceedings Article•
24 Aug 1981TL;DR: This paper discusses how to control and describe the smooth movement of a mobile robot which has two independent driving wheels (iDWs) that perform both steering and moving functions.
Abstract: This paper discusses how to control and describe the smooth movement of a mobile robot which has two independent driving wheels (iDWs) that perform both steering and moving functions. Robots which have an IDW leg system can move to any point by using any combinations of two basic operations: revolving and going straight.
It is easy to describe movement with two basic operations only, but this may not be sufficient to guarantee smooth motion. For instance, when the robot is moving, a slight modification to its track direction is impossible without stopping it. Smooth motions are also needed for minimizing the time required to complete the movement.
Theoretically, an IDW leg system can draw a circular track with radius 0 - ≪ if one controls the ratio of the two wheel speeds. This principle underlies much of the design of this control system.
The control system described in this paper uses three basic motion commands, supplemented by other commands that support these. A language has been designed for describing leg control algorithms. Examples of the usage of these commands and the language are shown here.
17 citations
TL;DR: In this paper, a linewidth as narrow as 4.5 MHz compared with the natural width of 10 MHz was obtained using phase switching of the optical field and gating of the photon counter.
Abstract: Subnatural linewidth in the optical transitions of Na ${D}_{2}$ lines was directly observed with use of phase switching of the optical field and gating of the photon counter. A linewidth as narrow as 4.5 MHz compared with the natural width of 10 MHz was obtained.
16 citations
TL;DR: Oguchi et al. as mentioned in this paper presented a self-consistently calculated band structure of a ferromagnetic semiconducting spinel Hg using the discrete variational $X\ensuremath{\alpha}$ method.
Abstract: The electronic band structure of a ferromagnetic semiconducting spinel Hg${\mathrm{Cr}}_{2}$${\mathrm{Se}}_{4}$ is self-consistently calculated by using the discrete variational $X\ensuremath{\alpha}$ method. The overall features of the band structure are quite similar to those of Cd${\mathrm{Cr}}_{2}$${\mathrm{S}}_{4}$ and Cd${\mathrm{Cr}}_{2}$${\mathrm{Se}}_{4}$ which have been calculated in the first paper of this series [T. Oguchi, T. Kambara, and K.I. Gondaira, Phys. Rev. B 22, 872 (1980)]. The fundamental energy gap is 1.8 eV, somewhat narrower than those of the Cd compounds. The narrowest band gap appears between the $d\ensuremath{\epsilon}$ and $d\ensuremath{\gamma}$ bands, and its width is 0.4 eV, much smaller than those of the Cd compounds. The top of the valence bands has the ${\ensuremath{\Sigma}}_{4}$ symmetry and the bottom of the conduction bands ${\ensuremath{\Gamma}}_{1}$. The spin polarization of the $3d$ orbitals of Cr is about 3.5, of which 0.5 comes from the $3d$ components mixed in the valence bands, while the spin polarization of the $4p$ orbitals of Se has the opposite sign, the magnitude of which is about 0.3.
15 citations
TL;DR: In this paper, it was shown that the boat benzene form is even more stable than the envelope or chair form benzene, and that it suffers 61.4 kcal/mol higher energy than that of flat benzene rings.
TL;DR: In this article, the magnetic susceptibility and NMR measurements of a CsCl type binary alloy CoTi were performed at temperatures between 4.2 and 800 K. The susceptibility and its temperature dependence was found to be large and the conventional Knight shift versus susceptibility plot was determined to be linear.
Abstract: The magnetic susceptibility and NMR measurements of a CsCl type binary alloy CoTi were performed at temperatures between 4.2 and 800 K. The susceptibility and its temperature dependence was found to be large and the conventional Knight shift versus susceptibility plot was found to be linear. From the slope of this K- χ plot the hyperfine field is determined to be a large positive value of +140 ±3 kOe/ µ B .
TL;DR: In this article, it was shown that the asymotic deficiency of any estimators in the restricted class D of the third order asymptotically median unbiased BAN estimators is given by the difference between the coefficients of order n-1 of the variances of the estimators.
Abstract: Summary
The notion of deficiency was introduced by Hodges and Lehmann It is known that best asymptotically normal (BAN) estimators are second order asymptotically efficient in the class A2 of all second order asymptotically median unbiased estimators
In this paper it is shown that the asymptotic deficiency of any two estimators in the restricted class D of the third order asymptotically median unbiased BAN estimators is given by the difference between the coefficients of order n-1 of the variances of the estimators
TL;DR: An analytical technique-chromatic aberration matching- is proposed that will ascertain the chromatic aberrations that are different and yet give the same polychromatic OTF for a specified spectral combination of the light source and the detector.
Abstract: To point out the danger of evaluating lenses on the basis of color-blind polychromatic OTFs, it has been shown that lenses with completely different chromatic aberrations can have the same polychromatic OTF. An analytical technique-chromatic aberration matching-is proposed that will ascertain the chromatic aberrations that are different and yet give the same polychromatic OTF for a specified spectral combination of the light source and the detector. A typical numerical example is given which supports the theory and the discussion.
TL;DR: In this article, the chemical composition, the stage number, and the identity period for ternary intercalation compounds prepared by the cathodic reduction of graphite in solution of KI in dimethylsulfoxide (DMSO) and their electrical properties are investigated.
Abstract: The chemical composition, the stage number, and the identity period, I c , are determined for ternary intercalation compounds prepared by the cathodic reduction of graphite in solution of KI in dimethylsulfoxide (DMSO) and their electrical properties are investigated. Gravimetry reveals that the chemical composition of the compounds is expressed as KC n (DMSO) 3 with n ≥ 24. Stepwise changes in the potential of graphite electrode on reduction are found to correspond to the formation of stage 2 compound KC 24 (DMSO) 3 with I c of 18.4 A and stage 4 compound KC 48 (DMSO) 3 with I c of 25.1 A. The spacing between adjacent carbon planes containing intercalate layer is 15.0 A. The electrical conductivity along the layer plane exhibits a significant increase followed by saturation with intercalate concentration. Compared with the corresponding binary compound KC n , the role of the organic molecule in the ternary compound is found to enhance the conductivity at the initial intercalation.
TL;DR: In this article, the authors introduced the twisted coordinate system and presented theoretical investigations of the existence of EM fields whose polarization plane rotates helically, and they derived the Hertz vectors suitable for this type of coordinate and general equations for TE and TM mode EM fields.
Abstract: This paper introduces the twisted coordinate system and presents theoretical investigations of the existence of EM fields whose polarization plane rotates helically. First, concrete expressions for vector operations are derived and the vector wave equations in homogeneous and isotropic media are given in terms of covariant and contravariant components. Then the EM wave whose polarization plane rotates with the coordinate axis is investigated. The results show that propagating rotating polarized wave fields do not exist if the electric field has only a single twisted coordinate component and that the TEM wave exists only as circular-polarized plane wave fields. By combining two circular-polarized waves propagating in opposite directions, parallel electric and magnetic fields exist. The Hertz vectors suitable for this type of coordinate are derived and general equations for TE and TM mode EM fields are obtained.
TL;DR: In this article, the authors compared PDB and COOD systems for the construction of data bases for 59Co-n.m.r. bibliographic and spectral data and found that the COOD system is better for the retrieval of spectral data, and for combination of data files on literature and chemical shifts.
TL;DR: It is suggested that the occurrence of these spontaneous movements would involve complex underlying factors, in part dependent on age and body size and blinking, facial expression and gross or small movements being mutually interrelated to some extent, and this relevance of the growth factor should be considered in studying free movements.
Abstract: The spontaneous movements and heart rate of subjects aged 3 to 11 years (nineteen boys and eleven girls) were observed while they sustained the standing at ease position for 10 min. The factors influencing the occurrence of spontaneous movements are discussed. Gross bodily movements (movements of the whole upper and lower extremities and the trunk) and small movements such as those of the hands, feet or neck, were less frequent among older children than among younger ones. Some of the latter showed relatively high mean heart rate levels during standing, but the frequency of spontaneous movements proved to be not always relevant to heart rate levels. A principal component analysis suggested that the occurrence of these spontaneous movements would involve complex underlying factors, in part dependent on age and body size (the growth factor) and blinking, facial expression and gross or small movements being mutually interrelated to some extent. This relevance of the growth factor should be considered in studying free movements.
TL;DR: In this article, the Ramaman spectra of SrTiO3 under a high DC electric field have been investigated for the ferroelectric soft mode at 77K and two split modes correspond to A2u and Eu modes in D4h symmetry rather than the expected field-induced coupling with the soft A1g mode for a 105K structural phase transition.
Abstract: Raman spectra of SrTiO3 under a high DC electric field have been investigated for the ferroelectric soft mode at 77K. Frequency splitting was observed above 20 kV cm-1 and the saturation of the integrated intensity occurred at 46 kV cm-1. Two split modes correspond to A2u and Eu modes in D4h symmetry rather than the expected field-induced coupling with the soft A1g mode for a 105K structural phase transition. The results suggest that field-induced anisotropy predominates over the intrinsic tetragonal anisotropy for Eext>or approximately=20 kV cm-1.
TL;DR: In this paper, the electric quadrupoles of the molecules are simulated by magnetic quadrupole and the molecular shapes thus obtained enable one to make molecular models, in which the electric quadruples of molecules were simulated by magnetron.
TL;DR: In this article, the characteristics of the generalized Van Vleck-Weisskopf-Frohlich type susceptibility (GVWF) are discussed, which can represent both an oscillator type and a relaxational (Debye) type of phonon mode, usually adopted in the analysis of Raman spectra of soft modes in structural phase transitions.
Abstract: The characteristics of the generalized Van Vleck-Weisskopf–Frohlich type susceptibility (GVWF) are discussed. It is shown that the GVWF can represent both an oscillator type and a relaxational (Debye) type of phonon mode, usually adopted in the analysis of Raman spectra of soft modes in structural phase transitions. It is also shown that a susceptibility for a Ising-spin system in a transverse field has a close resemblance to the GVWF.
01 Jan 1981
TL;DR: In this paper, the second-order asymptotic efficiency of MLE estimators has been discussed in terms of loss of information, and it has been shown that MLE attains the second order efficiency in the sense adopted here.
Abstract: Second order efficiency of asymptotically efficient estimators has been discussed by Fisher [20], Rao [37], [38] and others in terms of loss of information. Recently Chibisov [15], [16] has shown that a maximum likelihood estimator (MLE) is second order asymptotically efficient in this sense. Pfanzagl ([32], [33]) obtained that MLE attains the second order asymptotic efficiency in the sense adopted here. In this chapter we shall discuss second order asymptotic efficiency and proceed further to third order asymptotic efficiency. We shall show that the results can be extended to non-regular situations.
TL;DR: In this article, the electronic structures and binding energies of a nitrogen atom adsorbed at three symmetry sites on the Ta(100) and (110) surfaces were obtained by means of the extended Huckel molecular orbital method.
TL;DR: In this paper, the operation of current-access magnetic bubble domain propagate circuits has been simulated successfully by using a previously developed numerical scheme, and a method of testing bubble propagation with minimum length of the simulated time lapse has been established for both s = 0 parallel-azimuth and s = 1 uni-chiral bubbles.
Abstract: The operation of current-access magnetic bubble domain propagate circuits has been simulated successfully by using a previously developed numerical scheme. The drive field has been given analytically as H_{Z}(X,Y,Z) = - H_{p}\cos[2\pi(X/R_{X} - n(T)/4)]\exp[-(Y/R_{Y})^{b}] after a dual-conductor-sheet device which has bit period R X and track width in the order of 2R_{y} . A method of testing bubble propagation with minimum length of the simulated time lapse has been established for both s = 0 parallel-azimuth and s = 1 uni-chiral bubbles. Margin diagrams in terms of drive-field amplitude H p and dc bias field have been obtained for both bubbles at a drive frequency of 1MHz. The principle of calculation and the results of the simulation are given.
TL;DR: In this paper, a new method which produces energy from the ocean by utilizing the density difference of water, by means of a "chimney effect", is proposed, which concentrates on regions near estuaries where low density river water can be piped into the high density ocean.
TL;DR: In this paper, a modified M/G/l queueing system was discussed in which each customer receives certainly the normal service and subsequently receives the post-service with a certain probability p(0 ≦p ≦ 1) under the steady-state condition.
Abstract: In this paper, we discuss the modified M/G/l queueing system in which each customer receives certainly the normal service and subsequently receives the post-service with a certain probability p(0 ≦p ≦ 1) We work out the queue length process by applying Markov chain technique under the steady-state condition. The distribution function of the interoutput period is obtained, from which its first two moments are derived.
TL;DR: In this paper, the accuracy of numerical solutions and the constitutive modeling are discussed in relation to the analysis of inelastic problems involving material nonlinearities, focusing on the tangent stiffness method.
TL;DR: In this paper, a new electrooptic ceramic (Pb1-xAαx) {Nb2(3-α)x/5(ZryTi1-y) 1-x}O3 is proposed, where A=Ba or Sr.
Abstract: A new electrooptic ceramic (Pb1-xAαx) {Nb2(3-α)x/5(ZryTi1-y)1-x}O3 is proposed, where A=Ba or Sr. These ceramics sintered by the conventional hot-pressing method exhibit excellent optical chracteristics; namely their transmittances and transverse linear electrooptic coefficients being comparable to those of PLZT. Compositional and/or temperature dependences of dielectric constants, electromechanical coupling factors and lattice parameters have been measureed to elucidate the phase bondaries of these systems. It is also shown that lattice bacancies in the Pb sites deteriorate optical transparency considerably.